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Fan, Ting
Publications (7 of 7) Show all publications
Kagalwala, H. N., Tong, L., Zong, R., Kohler, L., Ahlquist, M. S. G., Fan, T., . . . Thummel, R. P. (2017). Evidence for Oxidative Decay of a Ru-Bound Ligand during Catalyzed Water Oxidation. ACS Catalysis, 7(4), 2607-2615
Open this publication in new window or tab >>Evidence for Oxidative Decay of a Ru-Bound Ligand during Catalyzed Water Oxidation
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2017 (English)In: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 7, no 4, p. 2607-2615Article in journal (Refereed) Published
Abstract [en]

In the evaluation of systems designed for 800 catalytic water oxidation, ceric ammonium nitrate (CAN) is often used as a sacrificial electron acceptor. One of the sources of failure for such systems is oxidative decay of the catalyst in the presence of the strong oxidant CAN (E-ox = +1.71 V). Little progress has been made in understanding the circumstances behind this decay. In this study we show that a 2-(2'-hydroxphenyl) derivative (LH) of 1,10-phenanthroline (phen) in the complex [Ru(L)(tpy)](+) (tpy = 2,2';6',2 ''-terpyridine) can be oxidized by CAN to a 2-carboxy-phen while still bound to the metal. This complex is, in fact, a very active water oxidation catalyst. The incorporation of a methyl substituent on the phenol ring of LH slows down the oxidative decay and consequently slows down the catalytic oxidation. An analogous system based on bpy (2,2'-bipyridine) instead of phen shows much lower activity under the same conditions. Water molecule association to the Ru center of [Ru(L)(tpy)](+) and carboxylate donor dissociation were proposed to occur at the trivalent state. The resulting [Ru-III-OH2] was further oxidized to [Ru-IV=O] via a PCET process.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2017
Keywords
mononuclear Ru catalysts, water oxidation, anionic ligands, 2-carboxyphenanthroline, ligand decay
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-206687 (URN)10.1021/acscatal.6b03278 (DOI)000398986700045 ()2-s2.0-85019738559 (Scopus ID)
Note

QC 20170509

Available from: 2017-05-09 Created: 2017-05-09 Last updated: 2018-09-19Bibliographically approved
Xie, H., Wang, L., Li, Y., Kuang, J., Wu, Z., Fan, T., . . . Fang, W. (2017). N-Insertion reaction mechanisms of phenyl azides with a hafnium hydride complex: a quantum chemistry calculation. New Journal of Chemistry, 41(12), 5007-5011
Open this publication in new window or tab >>N-Insertion reaction mechanisms of phenyl azides with a hafnium hydride complex: a quantum chemistry calculation
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2017 (English)In: New Journal of Chemistry, ISSN 1144-0546, E-ISSN 1369-9261, Vol. 41, no 12, p. 5007-5011Article in journal (Refereed) Published
Abstract [en]

Density functional theory (DFT) calculations were performed to investigate the detailed mechanisms for the N-insertion reaction of phenyl azides with a hafnium hydride complex. This reaction involves an intermolecular hydride transfer from the hafnium center of complex 1 (Cp2HfH2)-Hf-star to the terminal nitrogen atom of a phenyl azide. Subsequently, a 1,3 hydrogen shift from the N1 atom to the N3 atom takes place, accompanied by cleavage of the N2-N3 bond to provide amido complex 3 (Cp2HfH)-Hf-star(NHPh) and dinitrogen. A further reaction is related to the intermolecular hydride transfer from the hafnium center to the N1' atom of a second phenyl azide, followed by the formation of the final product, bis(amido) complex 9 (Cp2HfH)-Hf-star(NHPh)(2) via the liberation of the second dinitrogen, which is the rate-determining step with an overall barrier of 29.8 kcal mol(-1). Frontier molecular orbital theory analysis shows that phenyl azides are activated by nucleophilic attack by the hydride ligand, which is consistent with our previous studies of N2O activation by other transition-metal hydride complexes.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2017
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-210346 (URN)10.1039/c7nj00411g (DOI)000403340100043 ()
Note

QC 20170704

Available from: 2017-07-04 Created: 2017-07-04 Last updated: 2017-07-04Bibliographically approved
Kagalwala, H., Tong, L., Zong, R., Kohler, L., Ahlquist, M., Fan, T., . . . Thummel, R. (2017). Oxidative transformation of a Ru-bound ligand during chemically driven water oxidation. Paper presented at 254th National Meeting and Exposition of the American-Chemical-Society (ACS) on Chemistry's Impact on the Global Economy, AUG 20-24, 2017, Washington, DC. Abstract of Papers of the American Chemical Society, 254
Open this publication in new window or tab >>Oxidative transformation of a Ru-bound ligand during chemically driven water oxidation
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2017 (English)In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 254Article in journal, Meeting abstract (Other academic) Published
Place, publisher, year, edition, pages
American Chemical Society (ACS), 2017
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-226828 (URN)000429556701072 ()
Conference
254th National Meeting and Exposition of the American-Chemical-Society (ACS) on Chemistry's Impact on the Global Economy, AUG 20-24, 2017, Washington, DC
Note

QC 20180508

Available from: 2018-05-08 Created: 2018-05-08 Last updated: 2018-05-08Bibliographically approved
Fan, T., Duan, L., Huang, P., Chen, H., Daniel, Q., Ahlquist, M. S. G. & Sun, L. (2017). The Ru-tpc Water Oxidation Catalyst and Beyond: Water Nucleophilic Attack Pathway versus Radical Coupling Pathway.. ACS Catalysis, 7(4), 2956-2966
Open this publication in new window or tab >>The Ru-tpc Water Oxidation Catalyst and Beyond: Water Nucleophilic Attack Pathway versus Radical Coupling Pathway.
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2017 (English)In: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 7, no 4, p. 2956-2966Article in journal (Refereed) Published
Abstract [en]

Many Ru water oxidation catalysts have been documented in the literature. However, only a few can catalyze the O-O bond formation via the radical coupling pathway, while most go through the water nucleophilic attack pathway. Understanding the electronic effect on the reaction pathway is of importance in design of active water oxidation catalysts. The Ru-bda (bda = 2,2'-bipyridine-6,6'-dicarboxylate) catalyst is one example that catalyzes the 0-0 bond formation via the radical coupling pathway. Herein, we manipulate the equatorial backbone ligand, change the doubly charged bda(2-) ligand to a singly charged tpc- (2,2':6',2 ''-terpyridine-6-carboxylate) ligand, and study the structure activity relationship. Surprisingly, kinetics measurements revealed that the resulting Ru-tpc catalyst catalyzes water oxidation via the water nucleophilic attack pathway, which is different from the Ru-bda catalyst. The O-O bond formation Gibbs free energy of activation (AGO) at T = 298.15 K was 20.2 +/- 1.7 kcal mol(-1). The electronic structures of a series of Ru-v=O species were studied by density function theory calculations, revealing that the spin density of O-Ru=O of Ru-v=O is largely dependent on the surrounding ligands. Seven coordination configuration significantly enhances the radical character of Ru-v=O.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2017
Keywords
water oxidation, ruthenium complex, artificial photosynthesis, DFT calculation, water splitting
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-206688 (URN)10.1021/acscatal.6b03393 (DOI)000398986700082 ()
Note

QC 20170509

Available from: 2017-05-09 Created: 2017-05-09 Last updated: 2017-05-09Bibliographically approved
Ambre, R. B., Daniel, Q., Fan, T., Chen, H., Zhang, B., Wang, L., . . . Sun, L. (2016). Molecular engineering for efficient and selective iron porphyrin catalysts for electrochemical reduction of CO2 to CO. CHEMICAL COMMUNICATIONS, 52(100), 14478-14481
Open this publication in new window or tab >>Molecular engineering for efficient and selective iron porphyrin catalysts for electrochemical reduction of CO2 to CO
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2016 (English)In: CHEMICAL COMMUNICATIONS, ISSN 1359-7345, Vol. 52, no 100, p. 14478-14481Article in journal (Refereed) Published
Abstract [en]

Iron porphyrins Fe-pE, Fe-mE, and Fe-oE were synthesized and their electrochemical behavior for CO2 reduction to CO has been investigated. The controlled potential electrolysis of Fe-mE gave exclusive 65% Faradaic efficiency (FE) whereas Fe-oE achieved quasi-quantitative 98% FE (2% H-2) for CO production.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2016
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-200790 (URN)10.1039/c6cc08099e (DOI)000391272900032 ()2-s2.0-85006246960 (Scopus ID)
Note

QC 20170203

Available from: 2017-02-03 Created: 2017-02-02 Last updated: 2017-02-03Bibliographically approved
Xie, H., Fan, T., Lei, Q. & Fang, W. (2016). New progress in theoretical studies on palladium-catalyzed C−C bond-forming reaction mechanisms. Science China Chemistry, 1-16
Open this publication in new window or tab >>New progress in theoretical studies on palladium-catalyzed C−C bond-forming reaction mechanisms
2016 (English)In: Science China Chemistry, ISSN 1674-7291, p. 1-16Article in journal (Refereed) Published
Abstract [en]

This review reports a series of mechanistic studies on Pd-catalyzed C−C cross-coupling reactions via density functional theory (DFT) calculations. A brief introduction of fundamental steps involved in these reactions is given, including oxidative addition, transmetallation and reductive elimination. We aim to provide an important review of recent progress on theoretical studies of palladium-catalyzed carbon–carbon cross-coupling reactions, including the C−C bond formation via C−H bond activation, decarboxylation, Pd(II)/Pd(IV) catalytic cycle and double palladiums catalysis.

Place, publisher, year, edition, pages
Science in China Press, 2016
Keywords
C−H bond activation, decarboxylation, density functional theory, palladium catalysis, reaction mechanism, Carboxylation, Catalysis, Chemical activation, Chemical bonds, Chemical reactions, Palladium compounds, Bond-forming reactions, Cross coupling reactions, H-bonds, Palladium-catalyzed, Reductive elimination
National Category
Organic Chemistry
Identifiers
urn:nbn:se:kth:diva-197127 (URN)10.1007/s11426-016-0018-2 (DOI)000387571100012 ()2-s2.0-84979210739 (Scopus ID)
Note

QC 20161214

Available from: 2016-12-14 Created: 2016-11-30 Last updated: 2016-12-22Bibliographically approved
Fan, T., Zhan, S. & Ahlquist, M. S. G. (2016). Why Is There a Barrier in the Coupling of Two Radicals in the Water Oxidation Reaction?. ACS Catalysis, 6(12), 8308-8312
Open this publication in new window or tab >>Why Is There a Barrier in the Coupling of Two Radicals in the Water Oxidation Reaction?
2016 (English)In: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 6, no 12, p. 8308-8312Article in journal (Refereed) Published
Abstract [en]

Two radicals can form a bond without an energetic barrier. However, the radical coupling mechanism in ruthenium catalyzed water oxidation has been found to be associated with substantial activation energies. Here we have investigated the coupling reaction of [Ru=O(bda)L-2](+) catalysts with different axial L ligands. The interaction between the two oxo radical moieties at the Ru(V) state was found to have a favorable interaction in the transition state in comparison to the prereactive complex. To further understand the existence of the activation energy, the activation energy has been decomposed into distortion energy and interaction energy. No correlation between the experimental rates and the calculated coupling barriers of different axial L was found, showing that more aspects such as solvation, supramolecular properties, and solvent dynamics likely play important roles in the equilibrium between the free Ru-v=0 monomer and the [Ru-v=O center dot center dot center dot O=Ru-v] dimer. On the basis of our findings, we give general guidelines for the design of catalysts that operate by the radical coupling mechanism.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2016
Keywords
water oxidation, radical coupling, I2M, DFT, bda, catalysis, ruthenium
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-199489 (URN)10.1021/acscatal.6b02697 (DOI)000389399400034 ()2-s2.0-85046818884 (Scopus ID)
Note

QC 20170119

Available from: 2017-01-19 Created: 2017-01-09 Last updated: 2019-04-29Bibliographically approved
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